Threat of catastrophic vapor blast is gone, but other dangers loom near a massive chemical tank in California
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By Nina Giraldo, Taylor Romine, Emma Tucker, Alaa Elassar, Holly Yan, CNN
(CNN) — First, the good news: Fears of a calamitous vapor explosion that could destroy homes in Southern California have dwindled. But as crews grapple with an unpredicable chemical tank full of toxic material, other perils loom.
“The crisis is not averted.” Orange County Fire Authority Interim Chief TJ McGovern said Monday. “The evacuation zones are still in place. Please abide by those evacuation zones.”
About 50,000 residents were asked to flee their homes Thursday as the temperature and pressure escalated inside a tank at GKN Aerospace in Garden Grove. The tank contains 7,000 gallons of a chemical called MMA, which is used to make plastics and can cause myriad health problems upon exposure.
The potential consequences of increased heat or pressure teetered between two dreaded scenarios: a chemical leak that would infiltrate the soil and air with toxic material or a devastating blast that could damage homes and businesses.
A presidential emergency declaration has been signed for the situation, California Gov. Gavin Newsom announced Monday.
Crews worked overnight into Memorial Day to investigate a crack in the tank, which authorities said might alleviate pressure and prevent a disaster known as a BLEVE, or boiling liquid expanding vapor explosion.
“The biggest, catastrophic, worst-case scenario to the public and the first responders was the threat of a BLEVE … that threat has been eliminated,” McGovern said.
But “we still have threats that we’re mitigating right now,” the fire official said, including the “potential for an explosion that’s not as bad as a BLEVE” but still a risk to public safety, he said.
A volatile situation
The tank contains methyl methacrylate, or MMA, which is used to make resins and plastics, according to the Environmental Protection Agency. The chemical can cause skin and eye irritation as well as respiratory problems.
“There is still no chemical leak, as verified by continuous atmospheric monitoring,” the Orange County Fire Authority said Monday.
Still, some residents have reported symptoms of exposure. And some schools have closed and switched to online learning as a precaution.
The tank started showing signs of trouble Thursday, when heat and pressure started building up.
When MMA overheats, it starts a chemical reaction that is difficult to control inside a large tank, said Elias Picazo, a chemistry professor at the University of Southern California.
Authorities are trying to keep the tank as cool as possible to keep the chemical reactions happening inside the tank stabilized, said Elaine Bernal, a chemistry lecturer at California State University, Long Beach.
Almost 800 state and local first responders have been deployed to respond, said Gov. Gavin Newsom, including toxicologists, hazmat teams and public health sheltering experts.
Temperature gauge maxed out but chemical starting to cool
Methyl methacrylate’s “happy place” is 50 degrees Fahrenheit, and an increase in temperature could cause a leak or explosion, Orange County Fire Authority Division Chief and Unified Incident Commander Craig Covey said.
Officials aren’t sure exactly what temperature might cause the tank to ignite or explode, Orange County Fire Authority Captain Steve Concialdi said. They had no clue how hot it was inside the tank Sunday because the temperature gauge has already maxed out at 100 degrees.
By Monday morning, the temperature had stabilized and was falling, Covey said. “It is currently 93 degrees, down from 100 degrees. That is incredibly positive news as we turn the corner on this incident.”
With the largest threat out of the way, “crews are actively working right now on the next steps,” McGovern said.
“We still have product in there. We can’t physically see what the product is doing.”
Based on the latest temperatures inside the tank, fire officials believe the chemical has started to gel or solidify – which is exactly what they want.
“We know that the product will solidify (from) liquid to a solid form … but we don’t know how much of it has yet,” McGovern said.
GKN apologized to evacuated residents and businesses Sunday and said it’s working with emergency services and hazardous materials teams “to monitor the condition of the affected material and are working round the clock to mitigate the risk of a leak.”
“We are acutely aware of the uncertainty this incident is causing and sincerely apologise for the ongoing disruption to the local community,” the company said in a statement.
Theme parks such as Disneyland and Knott’s Berry Farm are close to but not included in the evacuation zone.
“At this time, there is no impact to Disneyland Resort due to this situation and the resort remains open to guests,” the park’s website said Monday. The park said it’s monitoring the situation and working with local authorities.
Newsom issued a state of emergency to support response operations. And Orange County District Attorney Todd Spitzer announced an anonymous tip line and reporting form for anyone with information about the incident or what led to it.
Residents sue tank owner
A couple who live in the evacuation zone filed a proposed class-action lawsuit against GKN Aerospace on Saturday, claiming the company negligently stored and handled MMA – leading to widespread disruptions for their community.
“Aside from just being evacuated, everything that they know and love is inside their home,” said attorney Filippo Marchino, who’s leading the class-action suit.
GKN Aerospace declined to comment on the litigation Sunday.
About 100 to 120 other residents have already expressed interest in joining the class-action case, Marchino said.
The lawsuit claims the company’s handling of the chemical caused dangerous conditions by creating an ongoing risk of fire, explosion, toxic chemical exposure and environmental contamination that affected tens of thousands of residents, businesses and schools.
‘I forgot to close the window … and I regret it’
Exposure to MMA can cause nausea, dizziness and “significant irritation” to the lungs and nasal passages, Orange County Health Officer Dr. Regina Chinsio-Kwong said.
The chemical can produce a fruit-like scent, although smelling it does not mean you have experienced enough exposure to have symptoms, she said in another update.
Officials said the chemical has not been detected in the air, but some residents said they’ve experienced symptoms.
“I forgot to close the window during the Thursday night, and I regret it,” said Stanton resident Van Ly, who evacuated Friday. “My throat and the inside of my nose feel sore, and my wife felt dizzy Friday night.”
Air should be safe outside the evacuation zone, Chinsio-Kwong said, urging people to leave the affected area.
Evacuated residents flock to shelters
Some school districts in the evacuation zone announced they would move to online learning. Garden Grove Unified School District said its 13 affected schools would remain closed “until further notice,” and district trustee Walter Muneton said the schools would shift to virtual learning.
The Red Cross opened a seventh shelter for evacuees Sunday as others in the area reached capacity for overnight stays.
Nearby hotels were also offering discounted rates over the holiday weekend.
Dawnedra Phillips, who lives in the evacuation zone, is taking warnings from officials seriously and staying at a shelter for evacuees in Cypress.
“I’m waiting it out, ‘cause here we have our community and we’re supporting each other the best that we can with what we have going on right now,” Phillips told CNN affiliate KABC. “I don’t care how old you are, it’s going to harm you one way or another.”
Past inspection led to violation and settlement
GKN Aerospace says its Garden Grove location is the “world’s leading provider of military transparency systems and commercial aircraft transparencies.” Aircraft transparency systems include canopies, windshields and windows.
A November 2020 inspection led to a violation notice and GKN Aerospace paying a nearly $1 million settlement.
The inspection by the South Coast Air Quality Management District, or AQMD – a regional pollution control agency – determined the site failed to keep required records of its VOC emissions, which degrade air quality when released at harmful levels, the agency said.
Inspectors also found GKN Aerospace operated new equipment without securing a permit and used existing equipment that did not match the description in the permit, the agency said. GKN also modified permitted equipment without applying for a permit change, which is required by the agency.
The company received two orders to fix the issues — in December 2020 and February 2021 — but failed to comply, the agency said. It led to a notice of violation in April 2021 and a civil penalty of about $900,000 paid by GKN, the agency said.
Since the violation, the South Coast Air Quality Management District said it has been “working closely with GKN to help resolve these permitting issues.”
In March 2025, GKN received two more notices to comply, AQMD said. The notices requested operating records and applications for registering certain equipment and a change in facility ownership.
When reached for comment, GKN reiterated its earlier statement about working to resolve the current situation at the facility that led to evacuations but did not address any previous issues.
This story has been updated with additional information.
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CNN’s Hanna Park, Lauren Mascarenhas, Maria Prieto Aguilar, Amanda Musa, Karina Tsui, Rebekah Riess and Sarah Dewberry contributed to this report.
